Tiotropium bromide is known from European Patent Application EP 418 716 A1 and has the following chemical structure:

Tiotropium bromide is a highly effective anticholinergic with a long-lasting effect, which may be used to treat respiratory complaints, particularly COPD (chronic obstructive pulmonary disease) and asthma. By tiotropium is meant the free ammonium cation.
Hitherto, there has been no explicit description in the prior art of salts of tiotropium other than the bromide. The halides and also the alkyl- and arylsulphonate of tiotropium should also be obtainable analogously using the method described in EP 418 716 (cf. Diagram 1). However, other salts of tiotropium cannot be produced using this method.
The aim of the present invention is to provide an alternative method of synthesis for preparing tiotropium salts which enables other tiotropium salts to be synthesised by a simple, non-aggressive method which is universally applicable.